I am only using 1 daughterboard. Sorry about the duc0 = 0 inclusion. It's
something I neglected to remove when I was editing the original file. I don't
think it should have any effect on what I am seeing though. I set the duc
frequency to 0 because I wanted to transmit at baseband. I've already built the
signal I want in the gr.vector, I just want the daughterboard to pass it as is.
I've managed to do that with usrp_siggen.py. By setting the -f option to 0 and
the -w option to some frequency, I get a waveform of the -w frequency at the
daughterboard output. I'm pretty sure (0, 0) is TXA, and (1, 0) is TXB. My
waveform does appear at the TXB output when I run the script. The problem is
the pulse duration I'm seeing is much shorter (about 1/10) than what I expect.
Regards
Lance
----- Original Message ----
From: David Scaperoth <[EMAIL PROTECTED]>
To: seph 004 <[EMAIL PROTECTED]>
Cc: discuss-gnuradio@gnu.org
Sent: Thursday, March 1, 2007 7:15:36 PM
Subject: Re: [Discuss-gnuradio] The shortest pulse length
On 3/1/07, seph 004 <[EMAIL PROTECTED]> wrote:
This is what I did:
def build_graph ():
nchan = 1
interp = 512
duc0 = 0
duc1 = 0
fs = 250e3 #2nd sample rate between
usb and dac
max_dev = 32e3 #1st sample rate divided by 4
(1st = 2nd sample rate)
gain = 16e3
k = 2 * math.pi * max_dev / fs
vec1 = Numeric.arange (0.624, 0.656, 0.0000128)
vsource = gr.vector_source_f(vec1, False)
fmmod = gr.frequency_modulator_fc (k)
amp = gr.multiply_const_cc(gain)
fg = gr.flow_graph ()
u = usrp.sink_c (0, interp, nchan)
tx_subdev_spec = (1, 0) #usrp.pick_tx_subdevice(u)
m = usrp.determine_tx_mux_value(u, tx_subdev_spec)
u.set_mux(m)
subdev = usrp.selected_subdev(u, tx_subdev_spec)
subdev.set_enable(True)
sample_rate = u.dac_freq () / interp
u.set_tx_freq (0, duc0)
u.set_tx_freq (1, duc1)
Are you trying to use one daughter boards(nchen=1)? Why did you set duc0 = 0?
that means your frequency will not be set at all. You do not need to do
set_tx_freq() twice if you are using one daughter board. you only need :
u.set_tx_freq (0, duc0) where duc0 is some frequency. Also, if you are using
the basic daughterboards, you need to make sure that you have the output
connector connect to TXA not TXB (according to your tx_subdev_spec)
Hope this helped.
David
____________________________________________________________________________________
Don't get soaked. Take a quick peak at the forecast
with the Yahoo! Search weather shortcut.
http://tools.search.yahoo.com/shortcuts/#loc_weather_______________________________________________
Discuss-gnuradio mailing list
Discuss-gnuradio@gnu.org
http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
